Apparatus for treating molasses



Jan. 20, 1953 s. T. HOYT APPARATUS FOR TREATING MOLASSES Filed Dec. 14, 1948 5 Sheets-Sheet l R o T N a v m BY .5l'nves Th'oyf ATTO RN EY Jan. 20, 1953 s. T. HOYT 2,626,055

APPARATUS FOR TREATING MOLASSES Filed Dec. 14, 1948 5 Sheets-Sheet 2 77 INVENTOR 5/07 s 7THogf BY A ATTORNE Jan. 20, 1953 s, HQYT 2,626,055

APPARATUS FOR TREATING MOLASSES Filed Dec. 14, 1948 V 5 Sheets-Sheet 5 FIE'L'- E I INVENTOR BY 5/mes Zfiogf 1 ATTORNEY 5. T. HOYT APPARATUS FOR TREATING MOLASSES Jan. 20, 1953 5 Sheets-Sheet 4 Filed Dec. 14, 1948 'INVENTOR 5/mesTHOyf ATTORNEY Jan. 20, 1953 's. 'r. HOYT APPARATUS FOR TREATING MOLASSES Filed Dec. 14,' 1948 s Sheets-Shet s FIE E INVENTOR 5/0765 7'. Hog) BY ATTO RN EY Patented Jan. 20, 1953 APPARATUS FOR TREATING MOLASSES Simes T. Hoyt, Honolulu, Territory of Hawaii,

assignor to Castle & Cooke, Limited, a corporation of Hawaii Application December 14, 1948, Serial No. 65,093

- This invention relates to the treatment of a liquid containing a granular solid to the end that the two be separated; more particularly, the present invention relates to the treatment of sugar massecuites or magmas and is intended to solve certain problems that have long been a source of trouble and expense.

As one of the steps in the recovery of sugar crystals from the associated mother liquor, it is usual to centrifuge the mixture to the end that the sugar crystal are collected and separated as completely as possible from the mother liquor, or molasses. The present invention makes it possible to effect the separation of crystals from mother liquor continuously rather than intermittently as at present, more rapidly, and in some cases more nearly completely than is now economically possible.

In processing low grade massecuites, a limiting factor is the viscosity of the mother liquor, the molasses. The two principal factors affecting viscosity of a massecuite are its composition and its temperature. A reduction in the water content increases the amount of sugar present in crystal form by reducing the amount which can be held in solution, but also increases the viscosity. A reduction in temperature has a similar effect. For proper centrifuging, massecuite must flow readily enough to permit it to build up quickly in an even ring around the inside of the centrifugal basket and to permit proper separation of mother liquor and sugar crystals.

Sugar solutions in general, and low grade massecuites in particular, can, under certain conditions, become supersaturated. It is a common practice to permit low grade massecuites to cool, after coming from' the vacuum pan, thus encouraging crystal growth. Under such conditions there is usually a, considerable degree of supersaturation. Before purging in the centrifugal, it is customary to dilute the massecuite by adding water or to heat it, to approximate the point of saturation in order to reduce the viscosity as much as possible and so make it easier to handle in the centrifugal. If, at any point, the dilution or the heating goes beyond the point of saturation, sugar crystals in that zone will be redissolved, hence cannot be recovered in the centrifugal. The greater the sub-saturation, and the longer the time the subsaturated mother liquor i in contact with sugar crystals, the greater the amount of redissolution.

I have found that it is possible to heat such a molasses in the presence of the sugar crystals and thereafter to purge in a centrifugal and to recover the sugar crystals substantially without loss due to redissolution, providing the heating i practically instantaneous and, provided further, that immediately upon the massecuite attaining such a high temperature, it is subject to the action of centrifugal force whereby the 5 Claims. (Cl. 21063) mother liquor and sugar crystals are separated in a very short period of time, e. g. of the order of one minute and preferably even less. I have found that the massecuite can be heated practically instantaneously by passing it in a continuous stream to the centrifuge, heating the stream immediately prior to its introduction into the centrifuge; the desired instantaneous heating I attain by passing the stream of massecuite over electrodes upon which a suitable current is impressed; the massecuite acts as a conductor between the electrodes and, due to its resistance, is heated practically. instantaneously whereby its viscosity is reduced suitably as to below 600 poises at the temperature of the massecuite. Thereafter, and with as little loss of time as is possible and within five seconds or less, the massecuite is subject to centrifugal force whereby the sugar crystals are separated from the mother liquor before these have time to pass into solution in the mother liquor. Because of the very short time during Which the heated molasses is in contact with the sugar crystals, it is possible to heatit to a materially higher temperature than present practice will permit without substantial loss by redissolution of crystal.

The invention is also concerned with the provision of a novel form of centrifuge particularly characterized by its simplicity of construction, its rugged nature, and its effectiveness in separating a solid from a liquid, as sugar crystals from the mother liquor in which they are carried.

It is a general and broad object of the present invention to provide a process enabling sugar crystals to be separated from their mother liquor.

A further object of the present invention is to provide the novel apparatus for heating a mother liquor substantially instantaneously so that solids therein do not have an opportunity to pass into solution prior to a separation operation to remove the solids from the heated liquid. This disclosure'contemplates that the mother liquor shall be afairly good conductor of electric current, as is the case with ordinary sugar massecuites. By a proper choice of voltage and frequency of the current used for heating, the desired heating effect can be obtained, even with non-conducting liquids. In such case, the electrodes would have to be suitably disposed, and the heating would be by the dielectric rather than by the resistance method.

The invention includes other objects and features of advantage, some of which, together with the foregoing, will appear hereinafter wherein the present preferred manner of practicing the process of this invention and the present preferred embodiment of the centrifuge of this invention are disclosed.

Referring to the drawings accompanying and formingapart hereof:

Figure 1 is a side elevation with portions of 3 the apparatusbroken away to illustrate certain constructions.

Figure 2 is a section taken along the line 2-2 in Figure 1.

Figure 3 is a fragmentary view illustrating a portion of the drive mechanism utilized.

Figure 4 is a plan view of the apparatus.

Figure 5 is a section taken along the line 5--5 of Figure 2.

Figure 6 is a section taken along the line 6--6 of Figure 2.

Figure 7 is a section taken along the line of Figure 6.

Figure 8 is a fragmentary view which i partly schematicto illustrate theconstruction of the electrodes and the supply of power.

Referring to the drawings, the apparatus in-' cludes a suitable base structure 6 on which is mounted the outer casing structure 9. which sup.- ports the horizontal frame members 8 which form the prinicpal supports for hearing I2, motor reducer I33, and frame 1, which. carries the main drive motor 6 I.

A hollow shaft H is mounted vertically of. the casing structure, being supported for rotation adjacent its lower end by a. bearing structure, generally indicated by thenumeral I2, secured by studs |3 upon one of the horizontal fram members 8. At its upper end, the hollow. shaft II is supportedby bearings I4 which is in turn secured upon inlet-casing I6.

Bearing- I2 includes a roller bearing 2| having its inner race mounteddirectly upon thehollow shaft thebearing 2| is resiliently supported by rubber ring. 22 provided between the outer race of the roller bearing. and casing 23, thelatter being directly secured by studs l3. to the-horizontal member 8 An annulus. 24, the loweredge of which projects downward within the top portion of casing 23, and which may be pulled downward against the rubber ring 22 by meansof bolts 26., serves to constrain the. bearing assembly 2|, on which the. rubber ring 22 is. firmly mounted, against any. undue movement. in any. direction, while permitting the small amountof oscillation of shaft H which is. necessary in a machine of this character. By. adjusting the. pressure of the annulus Zlonrubber ring 22, the damping ef.-. fectof therubber mountingmay be regulated as: required to give bestperformance. of the machine.

Mounted for rotation with the. hollow. shaft H, are. a. plurality. of circular-carrier plates. 3|. pp, sitioned. atdifierent. elevations. along the. shaft and surrounded by screenv 38.. Disposed symmetrically about. the. longitudinal axis. ofv thehollow shaft area plurality of centrifuge cells or baskets, 32, each in the. form of an open ended cylinder..

In the form. of device shownin. the, drawing, three. cells are employed, butmore or less than this. number can be utilized so long as they are symmetrically disposed aboutthehorizontal shaft.

I... Each, cell is ,mounted for rotation in, a roller bearing 33 ineach, carrier plate. 3 Within each cell are provided two fixed scrolls 34 woundin a.

suitable. direction .to. providev a. shelf. or support along which material can move downwardly when the cells are rotated. Between the scrolls 3.4 and the. inner wall, of each. basket, 32. are provided a plurality of strip members. |4| which extend parallel to. the axis of the basket and which are, provided in a spaced but over-lapping relation to; one another.. Each strip; includes a. plurality of fiat lugs I42 thereon fitting. into. oircularholes, 3L6; the. wall of the. basket; to. retain, the. Strip in place; the holes for supporting adjacent strips are staggered along the basket wall (Figure 2). Lugs I42 are at an angle to the strips (Figure 6) so that the latter extend away from the direction of rotation of the basket, that is, the strips extend, counterclockwise and the baskets rotate in a clockwise direction as viewed from the top of the cell. Each strip includes a plurality of projections I43 each of which projects downwardly from the outer edge of each strip to space the strip from that strip next adjacent and Which it overlies, as is shown in Figure 6. The opening between the strip is controlled by the amount of off-set in each projection and is of such size that solids such as the sugar crystals do not. pass through and yet the mother liquor can pass through freely. The scraping. effect, due tov the; rotation, tends to prevent any build-up of amass of crystals over an opening, and the direction of overlap of the strips, in relation to the direction of rotation, tend to prevent the crystals from moving toward the openings between strips, while liquid pressure, which is transmitted equally in all directions, causes the mother liquor or the molasses to flow outward between any pair of strip which is covered, and then out through the apertures 36 in the wall of each cell and thenceinto the space between adjacent carrier plates 3|, and finally outwardly through apertures 31 in the wall of screen 38. Liquid ejected from the screen 38 collects on casing 9 and is taken, off by annular trough 39 through openings 4| in casing 9 and into trough 42. The strips |4| are retained in place by the spring-like action of the scrolls 34.

Each cell is rotated with respect, to the hollow shaft II and also rotates with the shaft. This is accomplished by providing a gear 46, about the upper end of each cell 32, each gear being en-v gaged with a gear 41 upon the end of a shaft 48, the latter being mounted in bearings 49 and 5| for rotation in the hollow shaft II. The hollow shaft H is, cut away at 52 (Figure 5) at the elevation of and opposite to each gear 46 so that these can be driven by gear 4? during the rota-r tion of the cells with the hollow shaft Shaft 48 is driven with respect to hollow shaft to rotate the cells in the carrier plates 3| during their rotation about the hollow shaft H by the following mechanism: Mounted on theframe structure is a prime mover such as the electric motor 6| having a shaft 62 upon which are mounted'a first V belt pulley 63 and a second V belt pulley 64. A V belt pulley-66 is mounted on hollow shaft opposite V belt pulley 63 and a plurality of belts E? are trained about these to provide driving means between the motor 6| and the hollow shaft A V belt pulley 68 is provided opposite V belt pulley 64 and a plurality of V belts 69 are trained between these two; however, V belt pulley 68.is mounted by bearing 7|. upon the hollow shaft for rotation with respect to such. shaft (Figure 3). The lower end of thev belt pulley e8v includes a flange 12, the latter being secured by studslii to a housing or casing structure generally indicated at 14 and including a plate 76 which serves to support the housing generally indicated at 14 and which includes gear case 1'! and cover 8|; the housing rotates about the shaft with pulley 68. Projecting downward from thebottom of casing 74 and integral with it, is the smaller cylindrical portion 80, in which is mounted bearing 82., Cover 8,|. providesa means ofaccess to mountand;

adjust bearing 82, and a closure to prevent escape of lubricant from the casing I4.

Mounted for rotation in bearings 86 and 81 provided respectively in annular member I4 and plate I6 are shafts 88, each having affixed thereto a first set of gears 89 and a second set of gears SI. The first set of gears 89 are in mesh with a gear 92 formed upon an end of the hollow shaft II, while the second set of gears 9| are in mesh with the gear 93 provided upon the end of the solid shaft 48. The ratio of gears 89, 9|, 92, and 93 is such that, in conjunction with gears 46 and 41 and with pulleys and belts 64-6869 and 63-66-6'I, each cell is caused to rotate with respect to the plate carriers 3| in which it is mounted. Thus, a useful combination of speeds is: motor speed and pulleys, Nos. 64, and 68, 1750 R. P. M.; shaft II, pulley 66, rotating assembly 3|, 38, etc., 1275 R. P. M.; shaft 48, gears 93 and 41, 54 R. P. M.; gears 46 and cells 32, 10 R. P. M., with respect to plates 3I within which they rotate. The effect of such independent rotation of the cells is to distribute liquid fed thereto uniformly over the cell wall and to move the solids through the cell.

Mother liquor containing crystals is fed into the inlet casing I6 and thence down through tubes IIlI into the casing structure I02 suitably mounted on shaft II and the uppermost of plates 3|, and forming a part of the rotating assembly. Magma from the casing I62 is discharged by pipes I03 into each cell. In accordance with this invention, means are provided for heating the mother liquor substantially instantaneously. Each feed pipe IOI (Figure 2) is made of electrically non-conducting material and carries annular electrodes III] and III disposed with their inner annular faces flush with the inner surface or face of the feed pipe as is shown in Figures 2 and 8. A suitable electric potential is impressed on the electrodes to heat liquid flowing through the tube or feed pipe IIII. Electrodes III, near the middle of the tubes, are electrically hot, i. e., connected to a controllable source of electric potential, while electrodes IIIl, near the ends of the tubes, are electrically grounded, thus limiting the zone of passage of electric current through the massecuite substantially to the space within the feed pipes and eliminating the effect of stray currents, electrolysis, etc., which might otherwise cause damage to parts of the device. In most .cases, alternating current of commercially available frequency will be suitable and preferable.

In operation, the potential applied across electrodes III! and III is regulated to secure the desired temperature increase in the massecuite or other fluid; such regulation is necessary because the initial viscosity of the massecuite will affect its ease of heating as will its composition and, as either or both vary so is it desirable to increase or decrease the applied potential. With one massecuite fed at an initial temperature of 100 F., current was applied at the rate of 65.8 kw. to a stream fed at the rate of 250 pounds per minute; the massecuite was heated to 150 F. Depending on the initial viscosity, the initial temperature, and the composition of the massecuite, the potential can be suitably applied and regulated to raise the temperature of the massecuite substantially instantaneously and its viscosity reduced to less than 600 poises.

Solids discharged by each cell collect in the circular well I2I supported from annular trough 39 and are moved along the circular well I2I to the discharge outlet I22 by scrapers I23. These are rotated about the hollow shaft II by arms I 24 which depend from annular ring I26. The ring includes an annular channel I2I carried upon a plurality of bearings I28. A ring gear I29 is mounted in the channel and is driven by a gear I3I, the latter being supported upon a shaft I32 which is driven by a motor-reducer I33 by means of sprocket I34, chain I35, and sprocket I36 on the shaft I32.

To maintain the upper end of the casing structure 9 in alignment with the feed or inlet casing I6 and with the bearing I4 supporting the upper end of hollow shaft I I, a trough I4 la is provided upon casing 9. A pneumatic rubber tire and tube, generally indicated at MM, and such as are employed upon an automobile, are mounted upon the exterior of casing I6 with the periphery of the tire in engagement with the rough I4I a; in this manner, a flexible and yet relatively strong connection is provided between the two. The disposition of the tire in its mounting and the air pressure are advantageously such as to cause the weight of the rotating parts to be carried approximately half by bearing I4 at the top of the shaft II and half by bearing 2I, near the bottom of the same shaft.

From the foregoing, I believe it will be apparent that I have provided a relatively novel and simple centrifuge particularly useful in the treatment of various massecuites, magmas and the like, as well as a simple, rugged centrifuge particularly adapted to the separation of various liquids from solids carried therein.

I claim:

1. A centrifuge comprising a hollow shaft, means supporting said shaft for rotation about a vertical axis, a cell carrier mounted on said hollow shaft for rotation therewith, a plurality of cells disposed symmetrically about said shaft and mounted in said cell carrier for rotation in said carrier and with said carrier, each cell having an apertured wall for separating liquid from solids present therein, a gear on the upper end of each cell; a second shaft extending through said hollow shaft, a gear on said second shaft in mesh with each cell gear, means for rotating said hollow shaft at one speed, means for rotating said second shaft at a speed sufficient to rotate said cells in said cell carrier during rotation of said cell carrier including a casing rotatably mounted about said hollow shaft and said second shaft, a first gear on said hollow shaft, a second gear on said second shaft, a first set of planet gears rotatably mounted in said casing and enmeshed with said first gear, and a second set of planet gears rotatable with said first set of planet gears and enmeshed with the second gear.

2. A centrifuge comprising a hollow shaft, means supporting said shaft for rotation about'a vertical axis, a cell carrier mounted on said hollow shaft for rotation therewith, a plurality of cells disposed symmetrically about said shaft and mounted in said cell carrier for rotation in said carrier and with said carrier, each cell having an apertured wall for separating liquid from solids present therein, a gear on the upper end of each cell, a second shaft extending through said hollow shaft, a gear on said second shaft within said hollow shaft, said hollow shaft being relieved between each cell gear and said gear on said second shaft, said gear on said second shaft being in mesh with each cell gear, means for rotating said hollow shaft at one speed, means for rotating said second shaft at a speed suflicient to rotate said cells in said cell carrier during rotation of said first-:gear on. said hollow shaft, a second gear onv said second shaft, a; first setofplanet gears rotatably mounted in said casing and. enmeshed withsaid. first gear; and asecondset of planet gears rotatable with said firstxset. of planet gears and enmeshed with the second gear.

3. A centrifuge comprising a, hollow shaft apertured atzits upper end, means supporting said shaft for rotation about a vertical axis; a cell. carrier'mounted'on said: hollow shaft for rotation therewith, a plurality of cells disposedsymmetrically' about said shaft and mounted in said cell carrier for rotation in said carrier and with said carrier, eachv cell having an apertured wall for separating" the liquids from the solids present therein, a cell gear on the upper end of each cell extending through an aperture in said hollow shaft, a second shaft extendingthrough said hollow shaft, a gear-on one end of said second shaft for rotation within said hollow shaft in mesh with each cell gear, means for rotatin said'hollow shaft at one speed, means for rotating said second shaft at a speed approximating but different from said one speed to rotate said cell in said cell carrier during rotation of said cell carrier includinga casing rotatably mounted about said hollow shaft and said second shaft, a first gearon the other end of said hollow shaft, a secondgear on said second shaft, a first set of planet gears rotatably mounted in said casing and enmeshed with said first gear, and a second set of planet gears rotatable with said first set of planet gears and enmeshed with the second gear, means for feeding a fluid into each cell including a fluid heater including a tube having an inlet, an outlet and an inside surface, a first electrode maintained at ground potential and disposed flush with said inside surface adjacent said inlet, a second electrode maintained at ground potential and disposed flush with said inside surface adjacent said outlet, a third electrode disposed flush with said surface and between said first and said second electrode and at a potential to induce electrical current flow in liquid passing through said tube.

4. A centrifuge comprising a hollow shaft apertured atits upper end, means supporting said shaft for rotation about a vertical axis, a cell carrier mounted on said hollow shaft for rotation therewith, said cell carrier including a plurality of'spaced parallel support plates having a p111- rality of uniformly disposed circular apertures therein disposed about the shaft, a plurality of cellseach mounted for rotation in, the apertures in said plurality of plates for rotation in said carrier and with said carrier, each cell having an apertured wall for separating liquids and solids present therein, a cell gear on the upper end of. each cell extending through an aperture in said hollow shaft, a second shaft extending through said hollow shaft, a gear on one'end of said second shaft for rotation within said hollow shaft in mesh with each cell gear, means for rotating said hollow shaft at one speed to rotate the cell carrier and the cells about the hollow shaft as an-axis, means for rotating said second shaft. at a speed approximating but different fromsaid one speed to rotate said cells in said cell carrier during rotation of'said cell carrier, said means including a casing rotatably mounted about said hollow shaft and. said second shaft, a first gear on the other end of said hollow shaft, a second gear on said second shaft, a first set of planet gears rotatably mountedin said casing and enmeshedwith said first-gear, and, alsecondi set of; planet gears rotatable with said first set of. planet gears and enmeshed With the second gear.

5. A centrifuge comprising a hollow shaft apertured at its upper end, means supporting, said shaft for rotation about a vertical axis, a cell carrier mounted on said hollow shaft for rotation therewith, said cell carrier including a plurality ofspacedyparallel support plates having a plurality of circular apertures symmetrically disposed therein, aplura-lityof cells each mounted for-rotation the: apertures, in said plurality of plates for rotation in said carrier and with said carrier, each cell having an apertured wall for separating, liquids andsoli'ds present therein, a cell gearon the upper end of each cell extending, through an aperture in said hollow shaft, asecondshaft extending through saidhollow shaft, a.

gear on one end of said-second shaft for rotation within said hollow shaft in mesh with each cell gear, means for rotating said hollow shaft at one.

speed'to rotatethe cellcarrier and the cells about the hollow shaft as an axis, means for rotating said second shaft at-a speed approximating but different from said one speed to rotate thesaid cells in said cell carrier during rotation of said cell carrier, said means including a casing rotatably mounted about said hollow. shaft and said second shaft, a first gear on the other end of said hollow'shaft, a second: gear onsaid second shaft, a first set of planet gearsrotatably mounted in said: casing and enmeshed with said first gear, a second set of planet gears rotatable with said first set'of planet gears andv enmeshed with the secondv gear, means for feeding a heated fluid into each cell including a tube having an inlet, arroutlet, and an inside surface, a. first electrode maintained at ground potential and disposed flush with said inside surface adjacent said inlet, a secondelectrode maintained at ground potential and disposed flush with said inside surface adjacent said outlet, a third electrode. disposed flush with saidsurface and between said first and said second electrode and at a potential to induce electrical. current flow in fluid passing through said tube.

SIMES T.. HOYT.

REFERENCES. CITED.

The following references are of record in'the file of thispatent:

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